The problem which arises relates to the drawbacks that can result from vibration welding the reinforcing frame to the dashboard.
This connection takes place in the immediate vicinity of the line of weakness, and as a result the dashboard runs the risk of being damaged by the vibration.
In particular, the line of weakness in the wall runs the risk of becoming visible from the outside of the dashboard in spite of the decorative covering.
More generally, it can be considered that the step of vibration welding the reinforcing frame to the hard plastics layer of the dashboard is critical for the integrity, the strength, and the appearance of the dashboard at the location of or in the immediate vicinity of its cover that is designed to be invisible from the outside.